THE ASSOCIATION BETWEEN NULLIPARITY AND GESTATIONAL HYPERTENSION

The association between nulliparity and gestational hypertension was e xamined by analysis of the 1988 National Maternal and Infant Health Su rvey. Gestational hypertension was defined as the occurrence of two co nsecutive diastolic blood pressure readings greater than or equal to 9 0 mm Hg after 20 completed weeks gestation in the absence of proteinur ia in subjects normotensive prior to pregnancy. Preeclampsia was defin ed as gestational hypertension in the presence of significant proteinu ria. Using logistic regression, 110 subjects with gestational hyperten sion and 34 subjects with preeclampsia were compared with 4371 subject s free of all hypertensive disorders. Nulliparity was weakly associate d with an increase in the risk of gestational hypertension among white s (odds ratio, 95% confidence interval: 1.58 [0.92-2.74]) and not asso ciated with risk among blacks (1.09 [0.51-2.35]). Preeclampsia was str ongly associated with increased risk among whites (2.86 [0.94-8.73]) a nd blacks (2.94 [0.94-9.18]). The small increase in risk of gestationa l hypertension associated with nulliparity in contrast with the large increase in risk of preeclampsia suggests that these disorders may hav e a different etiology. (C) 1997 Elsevier Science Inc.